An ultrasound diagnosis device as one of image diagnosis devices is easy to handle and can noninvasively observe an arbitrary cross section in real time, and is thus very widely used for diagnosis. Meanwhile, an ultrasound image picked up by the ultrasound diagnosis device is sometimes compared with a cross sectional image (hereinafter referred to as a reference image) picked up by a different image diagnosis device such as an X-ray CT device or an MRI device that more clearly visualizes shape information for comprehensive diagnosis.
Particularly, an MRI image can be picked up by various parameters (T1 enhancement, T2 enhancement, diffusion imaging, or the like), and information that is not included in the ultrasound image can be added. Thus, it is useful to compare a real-time ultrasound image with a previously picked-up reference image.
For example, Patent Document 1 describes a method of correcting a shift in correspondence between a reference image and an ultrasound image. It is proposed that the disclosed correcting method is performed to correct the shift while it is small even if the shift occurs during image pickup, and thus the reference image and the ultrasound image are used in an easily linked state.
Patent Document 1: JP Patent Application Publication No. 2005-506006